I would try epoxy on and around the spiders first and see if it would hold up. For your surround issue I have found that gorilla glue works great. If the epoxy doesn't work try different spider configurations like 3 stiffs, 2 med,and 1 or 2 soft. Are you using a horn design enclosure? I would have to agree with unloading, but I don't think your problem is back pressure, I mean if it was I think you would fold the cone before you tore a spider with that kind of power.